Laser projector having safety lens for audience scanning

Abstract

A laser light projector includes a laser beam generated by a laser light source, a scanner associated with the laser light source and having one or more moving mirrors capable of scanning the laser beam along X-Y coordinates, a scan-fail monitor and a safety-lens. The safety-lens includes at least one optical power, and is positioned and arranged for increasing the safety of the projected light within audience areas by increasing beam divergence in the audience, while keeping beam divergence low above the heads of the audience, thus allowing mirror targeting to occur.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part application of U.S. utility patent application Ser. No. 12 / 791,326 filed on Jun. 1, 2010 for “Laser Projector for Audience Scanning,” which itself claims priority to U.S. Provisional Patent Application Ser. No. 61 / 324,014 for “Laser Projector and Safety Lens for Audience Scanning” having filing date Apr. 14, 2010 and is a continuation-in-part application of and claims priority to U.S. Utility patent application Ser. No. 11 / 814,310 for “Laser Projector for Audience Scanning” having filing date Jul. 19, 2006 filed in a National Phase Entry from Patent Cooperation Treaty Application PCT / US2006 / 001988 having filing date Jan. 9, 2006, which itself claimed priority to Provisional Patent Application Ser. No. 60 / 645,543 filed on Jan. 19, 2005 for “Audience Scanning Laser Projector,” the disclosures of which are herein incorporated by reference in their entirety, and all commonly owned.FIELD OF THE INVENT...

AI Technical Summary

Benefits of technology

The present invention allows for safer and more precise laser projections using small and low divergence beams. Additionally, the invention includes a fail-safe arrangement that prevents the removal of the safety lens, which could lead to the projection of high divergence beams. This reduces the risk to audience members and discourages unauthorized removal of the lens.

Problems solved by technology

If an intense laser beam were to stop scanning and directed on the pupil of a viewer's eye, retinal damage can occur if the beam has sufficiently high power and a sufficiently long dwell time.

Likewise, even if the beam is not stopped but is scanned across the pupil of an eye, it can still cause retinal damage if the beam power is high enough, or if the beam is scanning slowly enough.

If the beam were to stop scanning, producing zero velocity, or if the velocity were to otherwise drop below some preset threshold, this would be considered a “scanning failure.” Under a scanning failure condition, the beam may be completely turned off by the light beam modulator or by a shutter.

While scan-fail monitors provide some level of protection for the audience, there are a number of problems that still remain.

First, a scan-fail monitor does not provide automatic power level control in different regions of the scan field.

For example, scan fail monitors are not capable of allowing a higher power level over the audience's heads or below their eyes.

Second, scan-fail monitors can be easily “fooled” into believing that there is a safe condition when there is not, because they only monitor the rate of change of position and do not track the actual position of the beam.

However, in many instances, a 50% concentration of beam power could be hazardous.

Because the laser beam diameter is typically small in the audience, it means that no greater than around 5 milliwatts of laser power can be used to create the laser display, regardless of the sophistication of the scan-fail monitor.

If a higher power is used, the display will not be able to meet Class 1 standards for laser safety.

When the beam is greater than 7 millimeters, it means that the entire beam will no longer fit through the pupil of a viewer's eye and thus, not all of the laser beam power will be delivered to the retina if the laser beam does land on someone's eye.

However, this approach is not without problems: Placing a lens with negative optical power before or after the scanners will decrease the divergence in all parts of the scan field, including above the heads of audience members.

The larger beam diameter caused by the lens makes such beam targeting virtually impossible.

Another drawback is that, as the beam diameter is increased, the projected effect looks more cloudy and foggy, whereas the raw beam projected from the laser makes it look as though the light is cutting through the air like a knife.

However, an external mounting arrangement can also be tampered with.

However, as noted above, low divergence beams projected into the audience would be potentially hazardous, especially if the power of the laser is greater than 5 milliwatts.

Images